1. Field of the Invention
The present invention relates to a radiation imaging apparatus for capturing an image, a driving method therefor, a display control apparatus for displaying an image captured by a radiation imaging apparatus, a display controlling method, and a radiation imaging system that includes a radiation imaging apparatus and a display control apparatus.
2. Description of the Related Art
An X-ray imaging system that performs fluoroscopy in real time for interventional radiology (IVR) or other purposes typically includes an X-ray imaging apparatus, a display control apparatus, and a display apparatus. Traditionally, an image intensifier and an analog pickup tube or charge-coupled device (CCD) coupled to the image intensifier are used in such an X-ray imaging apparatus. The X-ray imaging apparatus transmits analog data to a display control apparatus through a video signal, and the display control apparatus displays an image captured in analog form on a display apparatus, such as a cathode ray tube (CRT) monitor. One example of such an X-ray imaging apparatus employing an image intensifier is described in Japanese Patent Laid-Open No. 2000-012280.
As recent digitization proceeds, an image intensifier (and analog pickup tube or CCD) in an X-ray imaging apparatus is being replaced by a flat panel sensor (FPS). With this trend, a CRT monitor or other monitors is being replaced by a high-definition liquid-crystal monitor using the digital visual interface (DVI), so a full digital system in which the process from imaging to displaying is digitized is being established.
However, for the above-described full-digital X-ray imaging system, if the speed of capturing an image is high or the resolution of image data is high in the X-ray imaging apparatus, a band for use in a communication unit that connects the X-ray imaging apparatus and the display control apparatus may be insufficient. This may cause a lag in transmission of image data from the X-ray imaging apparatus to the display control apparatus, and may result in a delay in displaying on the display apparatus.
By contrast, if image data is subjected to lossy compression or sampled in order not to cause a display delay, the image data will lose quality and thus the image displayed on the display apparatus will be degraded. This may lead to troubles in medical treatment, for example.
In particular, in an X-ray imaging system performing cine imaging, “cine-loop displaying” in which all images are displayed in a loop after the completion of the imaging and “real time displaying” in which display delay is less during the imaging are carried out. Therefore, it is necessary to satisfy both the conditions for cine-loop displaying and the conditions for real time displaying.